[piercho]

A lot of power supplies use electrolytic capacitors which don't last many years. That may not be your cause but it is a not uncommon cause of power supply failure. The main thing is to protect your stand and/or house from catching on fire. I put a line fuse on each of my fishtank power supplies, hopefully this cuts off the load before it knocks out the whole circuit by tripping the CB at the panel. And a 3 or 4 amp fuse will pop long before the 15 or 20 amp CB lifts. There are also arch-detecting CB comming available, but I have not researched or used these myself.

Scary story: a reef keeping coworker had an old 55G he was lighting with VHO. While the family was away, the ballast in the stand caught fire and the stand caught fire. The fire spread from the stand to the house and would have taken the whole house except that the fire cracked the tank and the spilling water put the fire out. He came home with his wife and promptly discovered the damage due to the soaked floor and smoke-blackened wall. To show you how resiliant this guy is, he promptly sent the wife out to buy a replacement tank to try and save some critters while he cleaned up the mess.

So Marc is right, you may have gotten very lucky.